It is the purpose of this project to develop methods for immunizing the vertebrate host against the sexual stages of malaria parasites of the genus Plasmodium which develop in the gut of the mosquito vector. Studies underway are concerned with: 1) vertebrate immunity factors which inhibit exflagellation, fertilization and oocyst development in the mosquito gut; 2) characterization of the host immune response to gamete antigens and the production of anti-gamete antibodies; 3) development of efficient methods of antigen production and methods for immunization of the vertebrate host against the sexual stages of the malarial parasite. BIBLIOGRAPHIC REFERENCE: Gwadz, R.W.: Malaria: Successful immunization against the sexual stages of Plasmodium gallinaceum. Science 193: 1150-1151, 1976.